Pterocarpus species

Family: Fabaceae (Papilionoideae)

There are two locally important species in this genus: Pterocarpus angolensis and P. tinctorius, both of which are managed and traded by the rural communities that MCDI support in south-eastern Tanzania. The two species, locally known as mninga, are grouped together for licensing purposes as they have very similar, orange-coloured timber. They also both produce characteristic spherical pods which have coarse hairs and are surrounded by a brown, circular wing approximately 12cm across.

Pterocarpus is the preferred timber for furniture throughout Tanzania on account of its working quality, durability and appearance. Much is made into planks in small-scale pit-sawing operations at the felling site. It has been the most important timber sourced from Kilwa District in recent years, based on both the volume harvested and license fee paid. Nonetheless, there are still sizable stocks of both species in the District.

Pterocarpus angolensis

In English, Pterocarpus angolensis is known as 'bloodwood' because of the red gum that drips like blood from damaged trees. In Swahili, the species is usually called mninga or mninga jangwa, but is also known by its Mwera name, mtumbati, locally in Kilwa District. 'Jangwa' means desert and refers to P. angolensis’ preference for drier habitats when compared to other species in the genus.

The Tree

P. angolensis is quite a common component of dry woodland such as miombo. It is one of the easiest species to identify, even when lacking leaves and flowers. The tree usually has a single, straight trunk, bark like crocodile skin (reticulate), and stark branches forming a flattened crown. For much of the year the branches are bare. The species can attain a height of nearly 30m, although few tall specimens are seen nowadays. In the rainy season it produces thick glossy leaves usually made up of 13 little leaflets. The fragrant, open yellow flowers are followed by distinctive bristly pods, which are characteristic of the genus. In the dry season the species can be identified by these pods, which often remain on the tree until the next year’s replacements are developing.

Timber

Physical & Woodworking Properties

Density (kg/m3)

Low (624)

Machining

good

Hardness (kgf)

Low (671)

Response to hand tools

Good

Bending strength (kg/cm3)

High (1,144)

Planing

Moderate

Durability

High

Turning

Good

Grain

Straight-interlocked

Resistance to splitting

Moderate

Texture

Medium-coarse

Resistance to impregnation

Moderate

Movement in service

Small

Resistance to insects

Very high

Other similar timbers

P. angolensis is similar to sapele (Entandrophragma cylindricum) and Andaman padauk (Pterocarpus dalbergioides) – both of which are heavily traded internationally – in terms of density, hardness, durability and machining. It also has similar stability and machining qualities to iroko (Milicia excelsa). African padauk (Pterocarpus soyauxii) is used as an alternative in industry, despite being harder and denser than P. angolensis.

Uses

Timber

P. angolensis was formerly an important timber resource of southern and east Africa, but stocks have severely declined in recent decades. The timber is mainly used for furniture, although it is also the preferred material for Swahili boat building and is used to make the traditional dhows associated with the east Indian Ocean. In South Africa the wood is used for carving.

Other uses

Some tribes in southern Africa use the gum of P. angolensis as body paint.

Pterocarpus tinctorius

Synonym: Pterocarpus holtzii

The Swahili names for this tree are mninga maji and mninga bondi. Maji means water and bondi means stream, so both names refer to the species’ preference for damper habitats than P. angolensis. The Mwera name mtumbati bondi is also frequently used. P. tinctorius grows to a larger size than P. angolensis, retains its leaves in the dry season and has rough flaking bark, so its appearance is very different. P. tinctorius is difficult to identify in the absence of visible pods, as it is extremely variable in form: many individuals branch low down, others are single-stemmed with an elongated trunk. The leaves are also usually high up, making this a difficult species to spot.